A&A Supplement series, Vol. 127, Mars I 1998, 369-375
Received January 20; accepted July 11, 1997
A.N. Ramaprakash
- R. Gupta -
A.K. Sen
- S.N. Tandon
Send offprint request: A.N. Ramaprakash
Inter-University Centre for Astronomy and Astrophysics, Post Bag 4,
Ganeshkhind, Pune - 411 007, India
Department of Physics, Assam University, Silchar - 788 001, India
Taking advantage of the advances in array detector technology,
an imaging polarimeter (IMPOL) has been constructed for measuring linear
polarization in the wavelength band from 400-800 nm. It makes
use of a Wollaston prism as the analyzer to measure
simultaneously the two orthogonal polarization components that define a
Stoke's parameter. An achromatic half-wave plate is used to rotate the
plane of polarization with respect to the axis of the analyzer so that the
second Stoke's parameter also can be determined. With a field of view corresponding to about 
for a
1.2 m, f/13
telescope, a sensitive, liquid-
cooled CCD camera as the
detector and a built-in acquisition and guidance unit, the instrument can be used for studying stellar fields or extended objects with an angular
resolution of 
. The instrumental polarization is less than
0.05% and the accuracies of measurement are primarily limited by photon
noise for typical observations.
keywords: instrumentation: polarimeters -- techniques: polarimetry -- polarization